4.0L Swap, Headlight WTF

[philzilla]

In the home stretch of my 4.0L Swap and I've run into an issue when wiring up the headlights.

94 Explorer is the donor and I pulled all the wiring.

When I connected the dash headlight plug to the headlight switch, the high beams would come on in Running Light position and Head Light position.

https://youtu.be/aw_UpWoUW4E (here is a link if the embedded player doesn't work)




So then I wired the plug to the switch one wire at a time to figure out where the problem was.

Connected B2 and R to the switch, pull the plunger once, the running lights turn on

Connected B1 and H to the switch, pull the plunger again, the headlights turn on

With just these 4 wires, the High Beam lever on the steering wheel works as expected, pull toward you and you get flash to pass, push away from you and it toggles on the brights.

Then, I connected "I" to the switch, which is supposed to control the brightness of dash lights and then all I get is brights when in running light and headlight position.

I put a switch in-between I to show the affect it has on the headlights when connected to the headlight switch.

Where the hell does I go?

 

[RonD]

If I am understanding it, which is a longshoot,

Check if the wire you are connecting to the "I" has voltage on it, that wire should just be a Ground from the dash lights, so low ohms to ground and 0 volts

If it has voltage then it would light up other lights on the head light switch circuit when attached

Other thing that can happen is ground at other lights is missing.
Check each Light wire going out of head light switch for a good ground, OHMS to ground, light bulbs are low ohms so you should see low ohms on all the wires to light bulbs
High ohms would indicate bad or no ground on that/those bulbs

 

[philzilla]

"I" is connected to the running lights, so when the plunger is in running light and head light position, "I" get's 12 volts from the "R" terminal.

It was my understanding from the diagram that "I" just dims the dash lights via the rheostat, which it does when turning the knob. But it seems like it is also turning on the headlight relays. So without "I" connected the headlights work perfectly, but no dash lights come on, and with "I" connected I only get brights.

I'll check for more grounds like you suggested and I think I am just going to have to bite the bullet and track that LT BLU/RED wire down to the source.